An adhesively bonded vehicle window provided with a premounted tear-away cord is known from DE-T2-689 11 272 (EP 0 367 662 B 1). The tear-away cord is made of a very strong material. It is laid in a profiled bead of synthetic material which adheres directly to the surface of the window pane in question. The profiled bead basically serves as an adhesive bead that links the window pane in a nonreleasable manner to the flange of the frame. By pulling on the tear-away cord, the profiled bead may be separated along its length, which also indirectly breaks the bond between the adhesive bead (which continues to adhere to the frame) and the window pane. The actual window pane then can be removed from the frame without being destroyed.
Very special attention has been devoted to limiting the separating force that must possibly be exceeded by the tear-away cord. Premature breaking of the relatively thin cord by excessive stressing must be prevented. For this reason, in one embodiment of this prior art, the tear-away cord is laid in a longitudinal groove of the profiled bead which, if it is desired, subsequently may be filled with a synthetic material after laying the cord. The groove constitutes a reduction in the cross-section, namely a site for future tearing, as it defines the cross-section to be separated. In other embodiments, the width of the area of adhesion of the profiled bead to the window pane is limited by special separating layers.
Also known (from DE-A1-3 730 345) is another similar window pane in which an adhesive bead intended to bond the pane to a frame is also applied to a profiled bead of synthetic material that itself adheres to the surface of the pane. In the embodiment in FIG. 6 of that document, this profiled bead may include a groove which serves for laying a tear-away cord, the groove being open on the side of the surface of the pane that is not turned toward the side of the profiled bead and not oriented toward the adhesive bead. Consequently, if tensile forces act on the tear-away cord, the strength of the wall of the groove, located between the cord and the adhesive bead, together with not inconsiderable friction, must be overcome and then the cord must in practice be pulled transversely with respect to the opening of the groove, in order to make it leave the groove and make it penetrate the adhesive bead.
In such configurations, an essential condition of the operation of the arrangement of the adhesive on the profiled bead is good mutual adhesion of the two materials that may, for example, both be based on polyurethane.
In an earlier known form (DE-A1 3 332 232), the tear-away cord is laid in a channel closed by a decorative or sealing section that extends parallel to an adhesive bead along the edge of a window pane, but without any adhesive bond to the edge of the pane. At one point, this tear-away cord is forced toward the inside through the adhesive bead, where it forms a purchase point for applying the necessary separating forces.
Direct incorporation of such a tear-away cord into the adhesive bead also is known (DE-A1 3 409 903), for example by laying it down at the same time as the adhesive bead is being extruded for nonreleasably joining the window pane to the flange of the frame. Vulcanization of a tear-away cord in a rubber frame of a window pane is known from the patent DE-PS-673 951. In this case, the entire cross-section of the adhesive bead or of the sealing frame must be separated, and this may require considerable forces to be applied meaning that the tear-away cord has to have a high tensile strength.